DFRobot Gravity: Analog Capacitive Soil Moisture Sensor- Corrosion Resistant Sensor Board for I2C 16x2 Arduino LCD

This product measures soil moisture levels by capacitive sensing, rather than resistive sensing like other types of moisture sensor. It is made of a corrosion-resistant material giving it long service life. Insert it into the soil and impress your friends with the real-time soil moisture data!
The product includes an on-board voltage regulator which gives it an operating voltage range of 3.3 ∼ 5.5V. It is compatible with low-voltage MCUs (both 3.3V and 5V logic). To make it compatible with a Raspberry Pi, an ADC converter is required.
This sensor is compatible with our 3-pin "Gravity" interface, which means it can be directly connected to the Gravity I/O Expansion Shield.